Board Thread:Pokémon Help/@comment-31398341-20171026040947/@comment-30155146-20171211063036

Fly is an HM. It's really accessable because it's given to you at a lv50 point in Adventure mode.

At low level play(All out attack only, no pivoting), it seems like fly actually allows dodging of moves.

As for marshadow - it outspeeds the majority of flying types, and the one mon that does outspeed, crobat, OHKOs it with brave bird